There are several methods for testing the vibration of different machines or vehicles in motion. To date, all of them have yield good results, however, they have the inconvenience that they don't test the vehicle when it is under actual movement conditions, for example, encountered on railroad tracks. Such circumstance prevents, a good test report since the behavior of a piece on the test machine is different from that of the same piece during routine work. Thus, one of the objectives of this invention is to provide a machine capable of testing the resistance to vibration of braking beams on railroad car trucks having the authentic possibility of repeating the real circumstances encountered in the routine movement of the brake beams.